Combine the ground beef with the onion soup packet and Worcestershire sauce in a large bowl. Divide and pat the mixture into 12 small patties, about 2 ounces each. Grill or cook on the stovetop to desired doneness, placing 2 small squares of cheese on each patty to melt at the end. Butter and lightly toast the buns. Spoon sauce onto the buns, then top with a burger patty and some shredded lettuce.